A pallet is a portable, horizontal, rigid platform used as a base for assembling, storage, stacking, handling and transporting goods as a unit load, often equipped with a superstructure. Conventional pallets are generally constructed of wood made by joining together as set of top and bottom deckboards fastened by nails or staples to a continuous, solid board often called a stringer or stringerboard. The pallet will have openings in the design to accompany fork truck or hand jack equipment to insert their forks between the top deck and bottom deck to lifting the pallet and its load off the floor. Pallets are generally square or rectangle with two-way or four-way entry into the pallet. A typical pallet size is 48 inches by 40 inches, i.e., 48 inch stringer or stringerboard and 40 inch deckboard.
Over Ninety percent (90%) of all pallets used in the United States are made of wood but these wood pallets have several disadvantages. First, labor and material costs involved in producing wooden pallets are relatively high and in recent years these costs have been increasing faster than inflation. As a result of these high costs, wooden pallets are often required to be reused either by the receiver or returned to the supplier which results in higher shipping costs (normally they are returned to the supplier empty). Second, because wood pallets weigh on the average forty (40) pounds this adds to the cost of shipping the load. The shipper is charged based on weight loading of the entire load including the pallet. Likewise due to the weight of the wooden pallet the operator may have difficulty manually moving the pallets. Third, some pallets are damaged during use while others are lost altogether through neglect or pilferage. The repair or disposal of damaged wood pallets adds to their cost. In some industries the typical wooden pallet is used on an average of no more than twice before it must be replaced or repaired. Typically a wood pallet will have four trips or reuses before disposal is necessary and disposal is already a major environmental concern.
Materials other than wood are being used in the design and manufacture of pallets such as metal, plastic and paper. The use of paper materials can be cost competitive to materials such as wood, metal and plastic while at the same time offering benefits that are not available through the use of traditional wood materials. The benefits of using paper materials are several fold. Paper products are lighter than wood, plastic or metal products and when formed into a honeycomb structure have remarkable crush strength. A paper pallet can be composed of four materials--paper sheet, paper honeycomb, paper corrugate and glue. Individually these products have limited, if any, ability to compete with wood products on a cost/benefit basis. However, by combining these materials in an effective design boosts the performance several fold while maintaining cost to similar wood products. Paper products are lightweight and easy to handle. Factory workers prefer working with products because of its light weight and surfaces that are smooth and splinter free. These features help reduce injury and time loss. Since our products have no nails, wood, metal or plastic components, they are biodegradable and can be disposed of without penalty charges or prohibitions from land fills or they can be baled and recycled to paper companies. Because of the ease of working with paper materials and the availability of various honeycomb structures, products can be manufactured in a variety of shapes and sizes to meet our customers' particular requirements. Because of the smooth surfaces and ability to adsorb energy, our products are very effective in reducing shipping damage to products.
The open literature shows several designs that use paper-based materials. Several companies have obtained U.S. patents in the 1970's and 1980's on pallet designs involving the use of paper materials. A summary of those patents is found in the following list:
______________________________________ U.S. Pat. No. Inventor Title ______________________________________ 3,661,099 Shelor Pallet Deck 3,650,459 Tucker Pallet Type Shipping Container 3,952,672 Gordon et al. Corrugated Disposable Pallet 4,319,530 Moog Pallet Having Runners with Dis- placable Sections 4,790,249 Webb Load-Carrying Pallet ______________________________________
None of these patents discloses a design for a paper pallet that meets the requirements of lightweight yet cost-effective design, and at the same time is capable of supporting relatively heavy loads.
U.S. Pat. No. 3,661,099 to Shelor suggests the use of corrugated board strips glued together perpendicular to the deck surface to form a core that is sandwiched between corrugated board sheets. The core laminate is comprised of multiplicity of planar strips, aligned in spaced, parallel relationship and separated by strips of thin solid sheet material. The deck is supported at corners by wood blocks that are attached to the deck by fasteners in order to function as a to form a pallet structure. The patent suggests that pallets fabricated from corrugate paper board versus a core laminated as suggested by Shelor made the pallets either too weak or too expensive.
U.S. Pat. No. 3,650,459 to Tucker discloses an invention related to the use of corrugated paper board to form a pallet-type shipping container with pallet feet formed of paper corrugate or molded plastic material disposed between the bottom tray of the container and a bottom panel.
U.S. Pat. No. 3,952,672 to Gordon et al. discloses a pallet of foldable material comprising a unitary outer structure folded about and joined to a unitary inner structure for easy assembly and disassembly. Both the inner and outer structures are made from corrugated paper board that connected by tuck tabs thereby requiring no external fastening means. The Gordon patent suffers from the same disadvantages as the prior art pallets noted above. First, the Gordon pallet requires a number of fabrication steps to machine the number of openings, tabs, tucks, etc. required to form the pallet. These fabrication steps add to the cost of the pallet and prevents it from competing on a cost basis with wood pallets. Additionally, the Gordon pallet does not have the necessary crush strength to support a typical wood pallet load of 2000 pounds dynamic loading. Wood pallets can easily handle loads above 2,500 pounds. However, less than ten percent (10%) of all pallet shipments made in the United States are above 2,500 pounds, and only thirty five percent (35%) of all shipments are over 2,000 pounds. Therefore, aA pallet designed to handle loads up to 2,000 pounds can adequately meet sixty five (65%) of all shipments. In order for the prior art pallets noted above to reach loadings of 2,500 pounds it becomes necessary to dramatically alter the structure of the pallet design which in turn increasing its costs and make them non-competitive to traditional wood pallets.
U.S. Pat. No. 4,319,530 to Moog describes a pallet design which does not employ a honeycomb top deck but utilizes a corrugate deck with honeycomb legs to support and provide strength to the pallet design. The Moog patent attempts to underlie with honeycomb pads and runners at least fifty percent (50%) of the surface area of the top deck. By increasing the amount of honeycomb support the pallet relies less on the rigidity of the deck to carry the load in the voids where no honeycomb material exists. However, with the large amount of exposed honeycomb material, the forks of the forklift or hand jack will easily puncture the honeycomb pads thereby reducing its strength and load-bearing capacity. While the patent of Moog attempts to occupy a proportionately greater area beneath the deck to provide loading-bearing support for heavy loads, it limits the space required by the forklift operators to position his fork blades without serious damage caused to the support structure.
U.S. Pat. No. 4,790,249 to Webb discloses a pallet that is also formed by through the use of corrugate and honeycomb materials that is lightweight and capable of supporting relatively heavy loads. Webb attempts to overcome Moog's deficiency by adding a bottom corrugate sheet to sandwich rigid tubular blocks or honeycomb blocks that provide strength to the pallet design and entry by the forks of the forklift. According to Webb, the invention allows the pallet to withstand side-shifting of the pallet when being shifted over the floor by the forklift. In addition, Webb claims the blocks which are not exposed are thereby not weakened by moisture and thus can be used on damp floors. Webb's design still requires that the block provide the load-bearing strength of the pallet and provide little room for the forks of the forklift to maneuver in an out of the pallet very easily. In addition, this design still suffers form the deficiencies of the prior art noted above in that the fabrication of the blocks and incorporation of the blocks into the structure is labor intensive and adds dramatically to the cost of the design.